1. ¹Department of Neurology and Neuroscience Program, Cerebral Vascular Disease Research Center, University of Miami School of Medicine, Miami, Florida, USA
2. ²Emergency Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
3. ³Department of Molecular Pharmacology, Stanford University School of Medicine, Stanford, California, USA

Correspondence: Dr MA Pérez-Pinzón, Department of Neurology (D4-5), PO Box 016960, University of Miami School of Medicine, Miami, FL 33101, USA. E-mail: perezpinzon@miami.edu

^*Both these authors contributed equally to this work.

Received 29 September 2004; Accepted 19 October 2004; Published online 16 February 2005.

Abstract

Protein kinase C (PKC) isozymes have been known to mediate a variety of complex and diverse cellular functions. PKC has been implicated in mediating apoptosis. Using two models of cerebral ischemia, cardiac arrest in rats and oxygen glucose deprivation (OGD) in organotypic hippocampal slices, we tested whether an ischemic insult promoted PKC cleavage during the reperfusion and whether the upstream pathway involved release of cytochrome c and caspase 3 cleavage. We showed that cardiac arrest/OGD significantly enhanced PKC translocation and increased its cleavage at 3 h of reperfusion. Since PKC is one of the substrates for caspase 3, we next determined caspase 3 activation after cardiac arrest and OGD. The maximum decrease in levels of procaspase 3 was observed at 3 h of reperfusion after cardiac arrest and OGD. We also determined cytochrome c release, since it is upstream of caspase 3 activation. Cytochrome c in cytosol increased at 1 h of reperfusion after cardiac arrest/OGD. Inhibition of either PKC/caspase 3 during OGD and early reperfusion resulted in neuroprotection in CA1 region of hippocampus. Our results support the deleterious role of PKC in reperfusion injury. We propose that early cytochrome c release and caspase 3 activation promote PKC translocation/cleavage.